HOW TO IDENTITY YOUR PULLEY DESIGN: The "long" water pump stands away from the timing cover about a "fingers width". The "short" design water pump almost touches the timing cover. The long water pump was commonly used on 1975 and newer Chevrolet small block engines with air conditioning, but can be used on older engines where the long water pump is being used. To use this pulley on older engines, all accessory brackets and pulleys must be designed for the long water pump.